Deposition method, deposition apparatus, and semiconductor device

Abstract

To deposit a metal oxide film with high dielectric constant.SOLUTION: A deposit method comprises step a) and step b). The step a) involves depositing a metal oxide film, specifically a ZrO2 film, a HfO2 film, or a mixed film of ZrO2 and HfO2. The step b) involves doping the metal oxide film with Te as a dopant.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a film forming method, a film forming apparatus, and a semiconductor device. [Background technology]

[0002] Patent Document 1 listed below discloses "a method for forming a metal oxide dielectric layer in the manufacture of an integrated circuit device, the method comprising the steps of: providing a substrate; depositing a metal oxide layer on the substrate by reacting a precursor containing one of the group consisting of metal alkoxides, halogen-containing metal alkoxides, metal β-diketonates, metal fluorinated β-diketonates, metal oxoacids, metal acetates, and metal alkenes with an oxidant gas in a chemical vapor deposition chamber; and annealing the metal oxide layer to densify it and complete the formation of the metal oxide dielectric layer in the manufacture of the integrated circuit device." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-246388 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides techniques for depositing high dielectric constant metal oxide films. [Means for solving the problem]

[0005] A film formation method according to one embodiment of the present disclosure includes steps a) and b). In step a), a ZrO film, a HfO film, or a mixed film of ZrO and HfO is formed as a metal oxide film. In step b), Te is doped into the metal oxide film. [Effects of the Invention]

[0006] According to the present disclosure, a metal oxide film with a high dielectric constant can be formed. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 illustrates monoclinic and tetragonal supercells doped with Te at various concentrations. [Figure 2] Figure 2 shows the results of the dielectric constant of Te-doped ZrO2 and HfO2 at various concentrations calculated using the PBE method, the PBE+U method (Ud=2 eV), and the PBEsol method. [Figure 3] FIG. 3 is a diagram showing the results of the X-ray diffraction spectrum of ZrO2 obtained by X-ray diffraction. [Figure 4] FIG. 4 shows the band structure of tetragonal ZrO2 (A) and the band structure of monoclinic ZrO2 (B) obtained by the PBE method. [Figure 5] Figure 5 shows the band structure of tetragonal ZrO2 doped with 3.1 at% Te (A), the band structure of tetragonal ZrO2 doped with 6.2 at% Te (B), the band structure of monoclinic ZrO2 doped with 3.1 at% Te (C), and the band structure of monoclinic ZrO2 doped with 6.2 at% Te (D), all obtained by the PBE method. [Figure 6] FIG. 6 shows the TDOS spectra of tetragonal ZrO2 doped with Te at 0 at%, 3.1 at%, 6.2 at%, and 12.5 at% (A), and the TDOS spectra of tetragonal HfO2 doped with Te at 0 at%, 3.1 at%, 6.2 at%, and 12.5 at% (B). [Figure 7A] FIG. 7A is a diagram illustrating the ion implantation method. [Figure 7B] FIG. 7B is a diagram illustrating the gas cluster ion beam method. [Figure 7C] FIG. 7C is a diagram illustrating the nanolaminate method. [Figure 7D] FIG. 7D is a diagram illustrating the dopant solution immersion method. [Figure 7E] FIG. 7E is a diagram illustrating the thermal diffusion doping method. [Figure 7F] FIG. 7F is a diagram illustrating the laser doping method. [Figure 7G] FIG. 7G is a diagram illustrating the flash lamp method. [Figure 7H] FIG. 7H is a diagram illustrating the deposited film method. [Figure 8] FIG. 8 is a diagram showing an example of a process flow of the film forming method according to the embodiment. [Figure 9] FIG. 9 is a diagram showing an example of the flow of the initial process in the film forming method according to the embodiment. [Figure 10] FIG. 10 is a block diagram schematically illustrating an example of the configuration of a film forming apparatus according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of a film formation method, a film formation apparatus, and a semiconductor device disclosed in the present application will be described in detail with reference to the drawings. Note that the disclosed film formation method, film formation apparatus, and semiconductor device are not limited to the embodiments.

[0009] [Dopant Considerations] Metal oxide films have traditionally been used as dielectric films or insulating films in semiconductor devices. Furthermore, as semiconductor devices become smaller and thinner, metal oxide films with higher dielectric constants are required as dielectric films or insulating films. Therefore, in an effort to obtain metal oxide films with higher dielectric constants, oxides of metals such as Ti (titanium), Zr (zirconium), Hf (hafnium), Y (yttrium), and Al (aluminum) have been widely studied. Among these, ZrO2 and HfO2 are considered promising metal oxide films due to their high dielectric constants. For example, in dynamic random access memories (DRAMs), metal oxide films made of metal oxides such as ZrO2 (zirconium oxide) and HfO2 (hafnium oxide) are used as capacitor materials.

[0010] Specifically, ZrO2 and HfO2 are known to be stable in the monoclinic (monoclinic) state at room temperature. Here, room temperature refers to a standard room temperature, for example, a temperature of 10 to 30°C. On the other hand, ZrO2 and HfO2 are known to be stable in the tetragonal (tetragonal) state at high temperatures exceeding 1000°C. Tetragonal has a higher dielectric constant than monoclinic, but it is difficult for it to exist stably at room temperature.

[0011] Furthermore, although the dielectric constant of such ZrO2 and HfO2 varies depending on the crystal structure, there is a limit to how much the dielectric constant can be increased.

[0012] In view of this situation, the present inventors have investigated doping to obtain a metal oxide film with a high dielectric constant. Specifically, doping a metal oxide film with an element having a radius different from that of the metal contained in the metal oxide film makes the crystal structure non-centrosymmetric, which is expected to increase the dielectric constant.

[0013] The present inventors have conducted extensive research to obtain a metal oxide film with a high dielectric constant by doping ZrO2 or HfO2 with a certain amount of some element. As a result, the present inventors have independently discovered that a metal oxide film with a high dielectric constant can be obtained by doping ZrO2 and HfO2 with Te (tellurium).

[0014] Specifically, the inventors discovered through trial and error using first-principles calculations as a calculation program that doping ZrO2 and HfO2 with Te can produce metal oxide films with high dielectric constants. First-principles calculations can accurately predict the stable structure, band structure, dielectric constant, and other physical properties of a material by determining the energy of the entire system, the electron wave function, and the forces acting on each atom based on information about the types and positions of the atoms that make up the material. For this reason, simulations using first-principles calculations have been widely used in recent years to explore new materials.

[0015] More specifically, we used the Projector Augmented-Wave (PAW) method, which is one of the methods used in the Vienna Ab initio Simulation Package (VASP) for first-principles electronic structure calculations, and the Perdue-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) functional for the exchange-correlation functional.

[0016] The dielectric constant is a physical property that indicates the degree of electrical polarization of a material when an electric field is applied to it. The dielectric constant is determined by three factors: orientation polarization, lattice polarization, and electronic polarization. In crystalline solids, however, it is determined by two factors: lattice polarization and electronic polarization.

[0017] The inventors calculated the dielectric tensor for each structure using Density Functional Perturbation Theory (DFPT) implemented in VASP. Since elements of the dielectric tensor other than the main diagonal can be zero or ignored, the average value of each main diagonal element of the dielectric tensor was used as the dielectric constant. That is, the value calculated from the following formula (1) was used as the dielectric constant (ε 0 ) was decided.

number

[0018] In equation (1), ε ion denotes the ionic (lattice polarization) contribution to the dielectric constant, and ε ∞ denotes the contribution of electrons (electronic polarization) to the dielectric constant, and ε ii denotes each diagonal element of the dielectric tensor.

[0019] First, to confirm whether such a calculation method can obtain a value close to the actual dielectric constant ε, the dielectric constant ε of cubic semiconductors C (carbon), Si (silicon), and SiC (silicon carbide) was calculated. 0The calculation conditions were a 12x12x12 k-point mesh, experimental values ​​for lattice constants, and a cutoff energy of 400 eV.

[0020] At C, the dielectric constant ε 0 The calculated value was 5.8, which is close to the measured value (ε) of 5.68 (Source: Chemical Handbook). 0 The calculated value was 13, which is close to the measured value (ε) of 12.10 (Source: Chemical Handbook). Furthermore, for SiC, the dielectric constant ε 0 is 10(ε ion = 3.29, ε ∞ = 6.96), which is close to the measured value (ε) of 9.72 (Source: Chemical Handbook). In other words, the above calculation method was used to obtain a dielectric constant ε 0 It was confirmed that this could be obtained.

[0021] Furthermore, the PBE method and the PBE+U method (for Zr atoms and Hf atoms, U d The dielectric constants of pure ZrO2 and HfO2 were calculated using the following equations: (=1, 2, 3, 4, 5, 6, 7, 8 eV). The calculation conditions were a cutoff energy of 520 eV, and k-point meshes of all monoclinic and tetragonal supercells (details of the supercells will be described later) were generated using VASPkit. The PBE+U method adds a correction for Coulomb repulsion to the PBE method, and the correction value U d The optimization of was also considered.

[0022] The dielectric constant ε of pure ZrO2 was measured using the PBE and PBE+U methods. 0 The calculated results are shown in Table 1, and the dielectric constant ε of pure HfO2 0 The calculated results are shown in Table 2. [Table 1] [Table 2]

[0023] As shown in Table 1, the PBE+U method (U d = 2 eV), the dielectric constant ε of pure tetragonal ZrO2 0 is calculated to be 36, and the dielectric constant ε of pure monoclinic ZrO2 0 was calculated to be 19. The measured dielectric constant (ε) of pure tetragonal ZrO2 is 32, and the measured dielectric constant (ε) of pure monoclinic ZrO2 is 12 (M. Delarmelina, M.G. Quesne, C.R.A. Catlow, Phys. Chem. Chem. Phys. 22, 6660-6676 (2020)).

[0024] Also, as shown in Table 2, PBE+U(U d = 2 eV), the dielectric constant ε of pure tetragonal HfO2 0 is calculated to be 39, and the dielectric constant ε of pure monoclinic ZrO2 0 was calculated to be 24. The measured dielectric constant (ε) of pure tetragonal HfO2 is 39, and the measured dielectric constant (ε) of pure monoclinic ZrO2 is 23 (M. Delarmelina, MG Quesne, CR A Catlow, Phys. Chem. Chem. hys. 22, 6660-6676 (2020)).

[0025] As shown in Tables 1 and 2, PBE+U(U d = 2 eV), the dielectric constant ε for pure ZrO2 and HfO2 is close to the measured value. 0 It was found that it is possible to obtain

[0026] Therefore, the inventors investigated the dielectric constant ε of ZrO2 doped with Te (tellurium), Ce (cerium), Ge (germanium), Se (selenium), and S (sulfur) at 12.5 at%. 0 In the calculation of , as above, the PBE+U method (U d = 2 eV) was used.

[0027] Here, with reference to FIG. 1, we will explain the doped monoclinic and tetragonal supercells used in our calculations. FIG. 1 illustrates the monoclinic and tetragonal supercells doped with Te at various concentrations. Specifically, the large spheres in the figure represent Zr or Hf atoms or Te atoms, and the small spheres in the figure represent oxygen atoms. Note that FIG. 1 shows an example in which Te is used as the dopant.

[0028] The inventors have prepared a supercell of ZrO2 and HfO2 doped with 12.5 at% Te by substituting one Zr or Hf atom of a 24-atom supercell (specifically, the supercell contains 8 Zr or Hf atoms and 16 oxygen atoms; monoclinic cell size: 1 × 2 × 1, tetragonal cell size: 1 × 1 × 2) with Te, as shown in Figure 1(A). Then, using the supercell, the dielectric constant ε 0 Hereinafter, calculations were performed assuming that the monoclinic and tetragonal structures were in the space group P42 / nmc and P21 / c, respectively.

[0029] Table 3 shows the results of the PBE+U method (U d = 2 eV) for the dielectric constant ε of ZrO2 doped with Te, Ce, Ge, Se, and S at 12.5 at%. 0 The calculation results are shown below. [Table 3]

[0030] As can be seen from Table 3, the dielectric constant ε of pure tetragonal and monoclinic ZrO2 0 are 37 and 19, whereas the dielectric constants ε of tetragonal and monoclinic ZrO2 doped with 12.5 at% Te are 0 The dielectric constants ε 1 and ε 2 were 77 and 38, respectively. In other words, it was found that the dielectric constant of ZrO2 increased by about two times by doping Te. In addition, the dielectric constants ε 1 and ε 2 were 77 and 38, respectively.0 The dielectric constants of tetragonal and monoclinic ZrO2 doped with Ge were 40 and 20, respectively, indicating a slight increase in the dielectric constant. 0 The dielectric constants of tetragonal and monoclinic ZrO2 doped with 12.5 at% Se were ε 37 and 23, respectively, indicating that the dielectric constants remained unchanged or increased slightly. 0 35 and 19, and it was found that the dielectric constant either decreased or remained unchanged. Furthermore, in the case of S, the dielectric constant ε 0 27 and 17, indicating that the dielectric constant decreases.

[0031] As explained above, monoclinic ZrO2, which can exist stably at room temperature, has a lower dielectric constant than tetragonal ZrO2. However, the results shown in Table 3 indicate that even monoclinic ZrO2, which can exist stably at room temperature, can have a higher dielectric constant than tetragonal ZrO2 by doping it with Te. In other words, these results indicate that Te can be used as a dopant to obtain metal oxide films with high dielectric constants.

[0032] Furthermore, the inventors have investigated the dielectric constant ε when doping Te at various concentrations, which has been found to be effective. 0 We examined changes in the following.

[0033] In this case, a supercell consisting of 48 atoms as shown in FIG. 1B (specifically, the supercell contains 16 Zr or Hf atoms and 32 oxygen atoms; monoclinic: 2 × 2 × 2, tetragonal: 2 × 1 × 2) was substituted with Te to create a supercell of ZrO2 and HfO2 doped with 6.25 at% Te. Using this supercell, a dielectric constant ε 0Furthermore, by substituting one Zr or Hf atom of a supercell consisting of 96 atoms as shown in Figure 1(C) (specifically, the supercell contains 32 Zr or Hf atoms and 64 oxygen atoms; monoclinic: 4 x 2 x 2, tetragonal: 2 x 1 x 4) with Te, a supercell of ZrO2 and HfO2 doped with 3.12 at% Te was prepared, and the dielectric constant ε was calculated using the supercell. 0 Table 4 shows the results of the PBE+U method (U d = 2 eV) for the dielectric constants ε of Te-doped ZrO2 and HfO2 at various concentrations. 0 The calculation results are shown below. [Table 4]

[0034] PBE+U method (U d =2eV), the dielectric constant ε of tetragonal ZrO2 0 The dielectric constant ε of monoclinic ZrO2 increased to 62 with 3.1 at% Te doping and reached a maximum value of 103 with 25 at% doping. 0 The doping of Te increased to 32 with 6.2 at% doping, and reached a maximum value of 38 with 12.5 at% doping. A similar tendency was also confirmed with the PBE method.

[0035] PBE+U method (U d =2eV), the dielectric constant ε of tetragonal HfO2 0 The dielectric constant ε of monoclinic HfO2 increased to 41 with 3.1 at% Te doping and reached a maximum value of 56 with 25 at% doping. 0 The value increased slightly to 24 with 3.1 at% Te doping, and reached a maximum value of 28 with 12.5 at% Te doping.

[0036] The results shown in Table 4 are consistent with reports that the dielectric constant ε of experimentally synthesized HfTe3O8 crystals is less than 44 (K. Yim, Y. Yong, J. Lee, K. Lee, H. Nahm, J. Yoo, C. Lee, C. Seong Hwang & S. Han, NPG Asia Materials 7, e190 (2015)). In other words, the results obtained in this study also suggest that the dielectric constant of tetragonal HfO2 doped with a high concentration of Te is approximately 43.

[0037] TeO2 is an oxide that exists stably as both tetragonal and monoclinic oxides. Tetragonal TeO2 has been reported to have a dielectric constant ε of 27 or less and a band gap of 3.3 eV or less (S. Guo, Z. Zhu, X. Hu, W. Zhou, X. Song, S. Zhang, K. Zhanga and H. Zeng, Nanoscale, 10, 8397-8403 (2018)). The results obtained by the present inventors show that when TeO2 is added to ZrO2, the dielectric constant increases to a value exceeding that of ZrO2 and TeO2.

[0038] Furthermore, the inventors have used another method (PBEsol method) to measure the dielectric constant ε of ZrO2 and HfO2 doped with Te at various concentrations. 0 Table 5 shows the dielectric constants ε of ZrO2 and HfO2 doped with Te at various concentrations calculated using the PBEsol method. 0 The calculation results for the PBEsol method are similar to those for the PBE and PBE+U methods. [Table 5]

[0039] Figure 2 shows the results of the PBE method, the PBE+U method (U d = 2 eV) and the dielectric constant ε of Te-doped ZrO2 and HfO2 at various concentrations calculated using the PBEsol method. 0The results are shown in Figure 2. In Figure 2, the horizontal axis represents the doping amount, and the vertical axis represents the dielectric constant. Furthermore, "t" in Figure 2 represents tetragonal, and "m" in Figure 2 represents monoclinic. As shown in Figure 2, it was found that the dielectric constant of tetragonal and monoclinic ZrO2 and HfO2 increases by doping with Te.

[0040] As described above, it was found that metal oxide films with high dielectric constants can be obtained by doping ZrO2 and HfO2 with Te.

[0041] Furthermore, tetragonal ZrO2 is preferably doped with 3 at% or more of Te, which allows for a metal oxide film with a high dielectric constant. Monoclinic ZrO2 is preferably doped with 6 at% or more and 25 at% or less of Te, which allows for a metal oxide film with a high dielectric constant.

[0042] In addition, tetragonal HfO2 is preferably doped with 3 at% or more of Te, which allows for a metal oxide film with a high dielectric constant.In monoclinic HfO2, it is preferably doped with 3 at% or more of Te, which allows for a metal oxide film with a high dielectric constant.

[0043] Furthermore, in Te-doped ZrO2 and HfO2, the tetragonal structure has a higher dielectric constant than the monoclinic structure. As explained above, tetragonal structures are less stable than monoclinic structures at room temperature. However, tetragonal ZrO2 and HfO2 can be obtained by reducing the film thickness to approximately 10 nm or less. Figure 3 shows the X-ray diffraction spectrum of ZrO2 obtained by X-ray diffraction. The upper part of Figure 3 shows the X-ray diffraction spectrum of ZrO2 with a 10 nm film thickness, and the lower part shows the X-ray diffraction spectrum of ZrO2 with a 20 nm film thickness. In Figure 3, the horizontal axis represents the diffraction angle (2θ / deg) and the vertical axis represents the peak intensity. Note that in Figure 3, T represents the peak due to the tetragonal structure, and M represents the peak due to the monoclinic structure. As shown in Figure 3, a tetragonal crystal structure can be obtained by reducing the film thickness to approximately 10 nm or less.

[0044] Furthermore, even when semiconductor devices are miniaturized, there is a strong demand for metal oxide films to suppress leakage current. Therefore, it is important that metal oxide films are insulators, i.e., have a large band gap. However, the band gap of insulator metal oxide films can be narrowed by adding dopants. Therefore, the inventors calculated the band structure and band gap of Te-doped ZrO2 and HfO2 using the PBE method and the PBE+U method.

[0045] Specifically, the PBE method was used to calculate the band gap of Te-doped ZrO2 and HfO2. Note that the PBE method has been reported to produce a lower band gap than the measured value, so the PBE+U method (U d =12 eV: ZrO2, U d = 11 eV:O), the band gaps of Te-doped ZrO2 and HfO2 were also calculated.

[0046] Table 6 shows the bandgaps of pure ZrO2 and HfO2, and Te-doped ZrO2 and HfO2 calculated using the PBE and PBE+U methods. [Table 6]

[0047] The PBE+U result for pure ZrO2 was below 5.3 eV, which was consistent with the 5.4 eV obtained by the mixed functional theory (HSE) method and experiment.

[0048] As shown in Table 6, the results obtained by the PBE and PBE+U methods indicate that the band gaps of Te-doped ZrO2 and HfO2 tend to decrease with increasing Te concentration. However, the band gap of tetragonal ZrO2 doped with 6.2 at% Te obtained by the PBE+U method is 4.2 eV, which is smaller than that of pure ZrO2 but still within the range of an insulator. Furthermore, the band gap of monoclinic ZrO2 doped with Te is also about 4 eV, indicating that it behaves as an insulator with a high dielectric constant.

[0049] Furthermore, although only results obtained for HfO2 by the PBE method have been obtained, the band gap value is larger than that of ZrO2 by the PBE method, which indicates that even Te-doped HfO2 behaves as an insulator with a high dielectric constant. As described above, it is preferable to dope ZrO2 and HfO2 with Te at a level between 3 at% and 15 at%; this allows for the production of an insulator.

[0050] We also calculated the band structures of pure tetragonal and monoclinic ZrO2 using the PBE method. The results are shown in Figure 4. Figure 4 shows the band structure of tetragonal ZrO2 (A) and the band structure of monoclinic ZrO2 (B) obtained by the PBE method. As shown in Figure 4, an indirect transition was observed at the Γ point in the results obtained by the PBE method, and the results were similar to the band structures of pure tetragonal and monoclinic ZrO2 previously reported (N. Barman, S. Tripathi, N. Ravishankar, KBR Varma, Solid State Communications 241, 7-13 (2016)).

[0051] Furthermore, the band structures of tetragonal and monoclinic ZrO2 doped with 3.1 at% and 6.2 at% Te were calculated using the PBE method. The results are shown in Figure 5. Figure 5 shows the band structure of tetragonal ZrO2 doped with 3.1 at% Te (A), the band structure of tetragonal ZrO2 doped with 6.2 at% Te (B), the band structure of monoclinic ZrO2 doped with 3.1 at% Te (C), and the band structure of monoclinic ZrO2 doped with 6.2 at% Te (D), all obtained by the PBE method.

[0052] As shown in Figure 5, the band structure obtained by the inventors confirmed that the conduction band and valence band are sufficiently separated even in Te-doped ZrO2, which means that Te-doped ZrO2 is an insulator.

[0053] Figure 6 shows the total density of states (DOS) spectra obtained by the PBE method. Figure 6 shows the TDOS spectrum (A) of tetragonal ZrO2 doped with Te at 0 at%, 3.1 at%, 6.2 at%, and 12.5 at%. Figure 6 also shows the TDOS spectrum (B) of tetragonal HfO2 doped with Te at 0 at%, 3.1 at%, 6.2 at%, and 12.5 at%. In Figure 6, the horizontal axis represents energy (eV) and the vertical axis represents the density of states.

[0054] As shown in FIG. 6, it was found that the band gap gradually decreased according to the Te doping amount.

[0055] As described above, by doping ZrO2 and HfO2 with Te, an insulator having a high dielectric constant can be obtained.

[0056] [Film forming method] In the film formation method according to this embodiment, a metal oxide film is formed. For example, a ZrO2 or HfO2 film is formed. Examples of techniques for forming the metal oxide film include atomic layer deposition (ALD), physical vapor deposition (PVD), chemical vapor deposition (CVD), and spin coating. However, the film formation method according to this embodiment is not limited to the above-mentioned methods.

[0057] Examples of methods for doping with a dopant include ion implantation, gas cluster ion beam, nanolamination, spin coating, dopant solution immersion, thermal diffusion doping, laser doping, flash lamp doping, and deposited film method.

[0058] 7A is a diagram illustrating the ion implantation method. In the ion implantation method, a substrate W, such as a semiconductor wafer having a metal oxide film formed thereon, is placed on a stage 30. In the ion implantation method, ions of a target impurity are generated by an ion source 31, and an acceleration unit (not shown) applies an electromagnetic field to accelerate the ions to form an ion beam 32, which is then focused by an electrostatic lens (not shown). In the ion implantation method, an AC voltage is applied laterally to the ion beam 32 to vibrate the ion beam 32 laterally, and the ions are irradiated onto the metal oxide film of the substrate W through small holes 34, thereby implanting the impurity ions into the metal oxide film.

[0059] FIG. 7B is a diagram illustrating the gas cluster ion beam method. In the gas cluster ion beam method, a substrate W on which a metal oxide film has been formed is fixed to a stage 40. In the gas cluster ion beam method, gas atoms of a target impurity are supplied to a nozzle 42 via a pipe 41, and a gas flow is ejected from the nozzle 42. In the gas cluster ion beam method, the pressure of the gas ejected from the nozzle 42 is controlled to eject gas clusters composed of hundreds to thousands of impurity gas atoms bonded together by van der Waals forces or the like from the nozzle 42. In the gas cluster ion beam method, the ejected gas clusters are ionized by an ionizer 43, and an electromagnetic field is applied by an accelerator 44 to accelerate the gas clusters into a gas cluster ion beam. In the gas cluster ion beam method, a gas cluster ion beam is passed through a magnetic field generated by a magnet 45, allowing particles of a target mass to pass through, and the gas cluster ion beam is neutralized by a neutralizer 46. In the gas cluster ion beam method, the diameter of the neutralized gas clusters is adjusted by the aperture 47, and the gas clusters that have passed through the aperture 47 are irradiated onto the metal oxide film of the substrate W, thereby implanting impurities into the metal oxide film.

[0060] 7C is a diagram illustrating the nanolaminate method. In the nanolaminate method, metal oxide films 51 and dopant films 52 are alternately laminated depending on the ratio of the dopant to be doped. Each layer may be formed by either ALD or PVD, or ALD and PVD may be switched for each layer.

[0061] Here, an example of a precursor used when forming a dopant film by ALD will be described.

[0062] In addition, when forming a HfO2 film, the precursor of Hf is, for example, HyALD (tri(dimethylamino)cyclopentadienylhafnium:C 11 H 23 Examples of such compounds include NHf), HOC (cyclopentadienyltris(dimethylamido)hafnium: HfCp(NMe2)3), TDMAH (tetrakis(dimethylamino)hafnium: Hf[N(CH3)2]4), and TEMAH (tetrakis(N-ethylmethylamino)hafnium). For example, the molecular structure of HyALD is represented by the following chemical formula (1). The molecular structure of HOC is represented by the following chemical formula (2). The molecular structure of TDMAH is represented by the following chemical formula (3). The molecular structure of TEMAH is represented by the following chemical formula (4). [ka]

[0063] Furthermore, when depositing a ZrO2 film, examples of Zr precursors include ZyALD (tri(dimethylamino)cyclopentadienylzirconium: (C5H5)Zr[N(CH3)2]3), ZAC (cyclopentadienyltris(dimethylamido)zirconium: ZrCp(NMe2)3), TEMAZ (tetrakis(N-ethylmethylamino)zirconium), and TDMAZ (tetrakis(dimethylamino)zirconium: [(CH3)2N]4Zr). For example, the molecular structure of ZyALD is expressed as shown in the following chemical formula (5). The molecular structure of TEMAZ is expressed as shown in the following chemical formula (6). [ka]

[0064] When forming a film of a dopant containing Te, examples of Te precursors include hydrogen telluride (H2Te) and diisopropyl tellurium (C6H6). 14 Te, dimethyl tellurium: Te(CH3)2, diethyl tellurium: Te(C2H5)2, dipropyl tellurium: Te(CH2CH2CH3)2, diisopropyl tellurium: Te(CH(CH3)2)2, dibutyl tellurium: Te(C4H9)2, di-tert-butyl tellurium: Te(C4H9)2, dipentyl tellurium: Te(C5H 11 )2, diphenyl tellurium: Te(C6H5)2, triphenyl tellurium: Te(C6H5)3, dimethylphenyl tellurium: Te(CH3)2(C6H5), diethyl ditelluride: Te2(C2H5)2, diisopropyl ditelluride: Te2(C3H7)2, dibutyl ditelluride: Te2(C4H9)2, diphenyl ditelluride: Te2(C6H5)2, etc.

[0065] Further, examples of precursors of Te include tricarbonyl tellurium (CO)3Te, tellurium trimethyl carbonate (Te(CH3)3CO2), tellurium butyl disalicylate (Te(C6H4(OH)CO2C4H9)2), etc. Furthermore, examples of precursors of Te include tetrachloride tellurium (TeCl 4、Examples include dichloride tellurium: TeCl2, dichlorodimethyl tellurium: TeCl2(CH3)2, tetrabromotellurium: TeBr4, dibromomethane tellurium: TeBr2(CH3)2, dichlorate tellurium: Te(ClO3)2, tetratrifluoromethyl tellurium: Te(CF3)4, tellurium triethylfluoroacetylacetonate: Te(C2H5)3(F3CCOCHCOCH3), tellurium triphenylphosphine: Te(C6H5)3P, and the like.

[0066] Furthermore, examples of precursors of Te include tellurium hexafluoroacetylacetonate: Te(C5HF6O2)2, tellurium acetylacetonate: Te(C5H7O2)2, and tellurium dioleate: Te(C 18 H 33 O2) 2、 Examples thereof include tellurium diacylhydrazide: Te(NHNH2)2, bis[diethylditrimethyl]tellurium: Te(EDD)2, and tellurium polygalchrome primarival sec-amino: TeEnPGCrPrSecAm.

[0067] Other examples of Te precursors include (R1R2R3Si)2Te, (R1R2R3Si)TeR4, (R1R2R3Si)TeN(R4R5), Me8Si4Te2, etc. In the chemical formulas of disilyltellurium, silylalkyltellurium, and silylaminotellurium as these Te precursors, R1, R2, R3, R4, and R5 are each independently hydrogen, or a linear, branched, or cyclic alkyl group having 1 to 10 carbon atoms, a vinyl group, or an aryl group.

[0068] As described above, when a film of a dopant containing Te is formed, examples of precursors of Te include inorganic tellurium compounds and organic tellurium compounds.

[0069] The precursors described above are merely examples, and the present invention is not limited to these. Any precursor may be used as long as it can form the respective films.

[0070] 7D is a diagram illustrating a dopant solution immersion method, in which a metal oxide film 61 formed on a substrate W is immersed in a dopant solution 62 containing a dopant, and the dopant is implanted into the metal oxide film 61.

[0071] 7E is a diagram illustrating the thermal diffusion doping method, in which a substrate W having a metal oxide film formed thereon is placed in a chamber 71, and while the substrate W is heated by a heat source 72 such as a heater provided in the chamber 71, a dopant gas containing a dopant is flowed into the chamber 71 to inject the dopant into the metal oxide film on the substrate W.

[0072] 7F is a diagram illustrating the laser doping method. In the laser doping method, a substrate W on which a metal oxide film has been formed is placed on a stage 82 in a chamber 81. A transmission window 83 that transmits laser light is provided above the stage 82 in the chamber 81. In the laser doping method, a dopant gas containing a dopant is flowed into the chamber 81 while irradiating the substrate W with laser light 84 through the transmission window 83, thereby injecting the dopant into the metal oxide film of the substrate W.

[0073] FIG. 7G is a diagram illustrating the flash lamp method. In the flash lamp method, a substrate W having a metal oxide film formed thereon is placed on a stage 92 in a chamber 91. A heater 93 is provided on the stage 92. The chamber 91 has a transmissive section 94 formed entirely above the stage 92 using a light-transmitting material. A flash lamp 95 is provided above the chamber 91. A reflector 96 that reflects light is provided above the flash lamp 95 so as to cover the flash lamp 95. The reflector 96 reflects light emitted upward from the flash lamp 95 downward and guides it to the substrate W. In the flash lamp method, the substrate W is heated by the heater 93, a dopant gas containing a dopant is flowed into the chamber 91, and the flash lamp 95 is turned on to implant the dopant into the metal oxide film on the substrate W.

[0074] 7H is a diagram illustrating the deposition film method. In the deposition film method, a sacrificial film 99 containing a dopant is formed on the upper surface of the substrate W on which a metal oxide film has been formed, and then the dopant in the sacrificial film 99 is diffused by heating, thereby implanting the dopant into the metal oxide film of the substrate W. After implanting the dopant, the sacrificial film 99 is removed by etching or the like.

[0075] In the film formation method according to this embodiment, a metal oxide film having a desired thickness may be formed by ALD, PVD, or CVD, and then the metal oxide film may be doped with a dopant. Alternatively, in the film formation method according to this embodiment, a metal oxide film may be formed to a desired thickness by alternately repeating the formation of a metal oxide film by ALD, PVD, or CVD and the doping of the metal oxide film with a dopant. The metal oxide film can be doped with a dopant in any of the above-mentioned ion implantation, gas cluster ion beam, dopant solution immersion, thermal diffusion doping, laser doping, flash lamp deposition, and deposited film methods.

[0076] Next, an example of a specific flow for forming a metal oxide film using the film forming method according to the embodiment will be described. The following describes an example in which a ZrO2 film, a HfO2 film, or a mixed film of ZrO2 and HfO2 is formed as a metal oxide film in one chamber by the nanolaminate method while doping with Te. Figure 8 is a diagram showing an example of a process flow for the film forming method according to the embodiment. A substrate W to be formed on is placed in the chamber, and the chamber is depressurized to a predetermined vacuum level, and then the process shown in Figure 8 is carried out.

[0077] In step S10, gases used to deposit one or both of Zr and Hf are supplied to the chamber. For example, when depositing a ZrO2 film, TDMAZ is supplied. When depositing a HfO2 film, TDMAH is supplied. When depositing a mixed film of ZrO2 and HfO2, TDMAZ and TDMAH are supplied.

[0078] In step S11, a purge gas is introduced to evacuate the chamber. Step S11 may be omitted. Alternatively, in step S11, a plasma may be generated while an oxidizing gas is introduced, similar to step S14 described later, to deposit a film of ZrO2, HfO2, or both.

[0079] In step S12, a precursor of Te is supplied to the chamber, and in step S13, a purge gas is introduced to evacuate the chamber.

[0080] In step S14, a plasma is generated while an oxidizing gas such as O3 gas or O2 is flowing to oxidize Zr, Hf, etc., forming a film of ZrO2, HfO2, or both, and also oxidizing the Te precursor. In step S15, a purge gas is flowed to evacuate the chamber. Note that step S15 may be omitted.

[0081] In the film formation method shown in FIG. 8, steps S10 to S15 are repeated until a target film thickness is reached, thereby forming a metal oxide film of Te-doped ZrO2 and / or HfO2.

[0082] In the film forming method shown in FIG. 8, steps S10 to S15 are repeated until the desired film thickness is achieved, but the method is not limited to this.

[0083] In order to more stably form a metal oxide film having a tetragonal crystal structure, the film formation method according to the embodiment may perform the following initial treatment before forming the metal oxide film. Fig. 9 is a diagram showing an example of the flow of the initial treatment in the film formation method according to the embodiment.

[0084] A thin film 20 of either or both of ZrO2 and HfO2 is formed on a substrate W (FIG. 9(1)). FIG. 9(1) shows the state in which the thin film 20 of ZrO2 has been formed on the substrate W. The crystal structure of the ZrO2 in the thin film 20 is monoclinic. "ZrO2(m)" indicates that the crystal structure of ZrO2 is monoclinic.

[0085] The ZrO2 or HfO2 thin film 20 is treated with sulfuric acid or phosphoric acid, and the surface is coated with SO4 2- PO4 3- ions are carried (FIG. 9(2)). FIG. 9(2) shows that ZrO2(m) of the thin film 20 has been treated with sulfuric acid. Note that FIG. 9(2) shows an example in which ZrO2 or HfO2 of the thin film 20 is treated with sulfuric acid or phosphoric acid, but the present invention is not limited to this. In FIG. 9(2), ZrO2 or HfO2 of the thin film 20 may be treated with any one of the chemical solutions of sulfuric acid, phosphoric acid, hydrogen peroxide, dilute hydrofluoric acid, hydrochloric acid, and ammonia, or a mixture of two or more of these chemical solutions.

[0086] The processed substrate W is baked at 500°C or higher (Figure 9(3)). By baking, the crystal structure of ZrO2 and HfO2 in the thin film 20 becomes tetragonal. In Figure 9(3), the crystal structure of ZrO2 in the sulfuric acid-treated thin film 20 becomes tetragonal. "ZrO2(t)" indicates that the crystal structure of ZrO2 is tetragonal.

[0087] The sulfuric acid and phosphoric acid remaining on the surface of the substrate W are removed by washing and drying (FIG. 9(4)). ZrO2 or HfO2 having a tetragonal crystal structure is formed on the thin film 20 as a template. In FIG. 9(4), ZrO2 having a tetragonal crystal structure is formed on the thin film 20.

[0088] On the thin film 20 having a tetragonal crystal structure, a film 21 of one or both of ZrO2 and HfO2 is formed in the same manner as the thin film 20 by the film formation method according to the embodiment (FIG. 9(5)). In FIG. 9(5), a film 21 of ZrO2 having a tetragonal crystal structure is further formed on the thin film 20 having a tetragonal crystal structure. In this way, by forming the film 21 on the thin film 20 having a tetragonal crystal structure, the film 21 having a tetragonal crystal structure can be stably formed.

[0089] Note that the process of Figure 9(4) is not essential and may be omitted. Figure 9(5)' shows a case where Figure 9(4) is omitted and a film 21 of one or both of ZrO2 and HfO2 is formed on a thin film 20 on which sulfuric acid and phosphoric acid remain, similar to the thin film 20, by the film formation method of the embodiment. In Figure 9(5)', a film 21 of ZrO2 with a tetragonal crystal structure is further formed on the thin film 20 of ZrO2 on which sulfuric acid and phosphoric acid remain. Even in this case, the film 21 with a tetragonal crystal structure can be stably formed.

[0090] By performing the initial process of forming the thin film 20 having a tetragonal crystal structure on the substrate W in this manner, the thin film 20 or film 21 of metal oxide having a tetragonal crystal structure can be stably formed from the vicinity of the interface with the substrate W.

[0091] [Configuration of Film Forming Apparatus 10] Next, an example of a film formation apparatus 10 for performing film formation by the film formation method according to the embodiment will be described. Fig. 10 is a block diagram showing a schematic configuration of an example of the film formation apparatus 10 according to the embodiment. The film formation apparatus 10 has a film formation section 11 and a doping section 12.

[0092] The film forming unit 11 is a unit that forms a metal oxide film. The film forming unit 11 has a chamber and is configured to be able to form a metal oxide film in the chamber by any one of ALD, PVD, and CVD. For example, the film forming unit 11 can be configured using a film forming apparatus or the like that can perform any one of ALD, PVD, and CVD film formation processes.

[0093] The doping section 12 is configured to dope the metal oxide film with a dopant.

[0094] The doping unit 12 may be provided in the chamber of the film formation unit 11, or in a chamber separate from the chamber of the film formation unit 11. When the doping unit 12 performs doping by ion implantation and the film formation unit 11 forms a metal oxide film by ALD or PVD, the doping unit 12 is provided in a chamber separate from the chamber of the film formation unit 11. On the other hand, when the doping unit 12 performs doping by ion implantation and the film formation unit 11 forms a metal oxide film by PVD, the doping unit 12 may be provided in the chamber of the film formation unit 11, or in a separate chamber. When the doping unit 12 performs doping by any of a gas cluster ion beam method, a dopant solution immersion method, a thermal diffusion doping method, a laser doping method, a flash lamp method, and a deposited film method, the doping unit 12 is provided in a chamber separate from the chamber of the film formation unit 11. When the doping unit 12 performs doping by the nanolaminate method, the doping unit 12 is provided in the chamber of the film forming unit 11 .

[0095] When the film formation unit 11 and the doping unit 12 are configured as separate chambers, the film formation apparatus 10 is provided with a transport mechanism such as a transport arm for transporting the substrate W. When a metal oxide film is formed, the film formation apparatus 10 transports the substrate W to the film formation unit 11 by the transport mechanism, and when doping with a dopant, the transport mechanism transports the substrate W to the doping unit 12.

[0096] When a metal oxide film having a desired thickness is formed and then doped with a dopant, the film forming apparatus 10 forms a metal oxide film having a desired thickness in the film forming section 11, and then dopes the metal oxide film with a dopant in the doping section 12.

[0097] On the other hand, when a metal oxide film is formed by alternately repeating film formation and doping, the film formation apparatus 10 alternately repeats the formation of a metal oxide film in the film formation section 11 and the doping of a dopant into the metal oxide film in the doping section 12 to form a metal oxide film to the desired thickness.

[0098] The film formation apparatus 10 forms a metal oxide film on the substrate W by the film formation method according to the present embodiment. For example, the film formation apparatus 10 forms a metal oxide film as a dielectric film or an insulating film of a semiconductor device to be manufactured on the substrate W by the film formation method according to the present embodiment. For example, the film formation apparatus 10 forms a metal oxide film as a dielectric film or a gate insulating film of a capacitor of the semiconductor device by the film formation method according to the present embodiment. In this way, the film formation apparatus 10 can form a metal oxide film with a high dielectric constant. By being able to form a metal oxide film with a high dielectric constant as a dielectric film or an insulating film of a semiconductor device in this way, leakage current in the metal oxide film can be suppressed even when the semiconductor device is miniaturized.

[0099] [effect] The above describes the embodiment. As described above, the film formation method according to the embodiment includes step a) (e.g., steps S10 and S14) and step b) (e.g., steps S12 and S14). In step a), a ZrO2 film, a HfO2 film, or a mixed film of ZrO2 and HfO2 is formed as a metal oxide film. In step b), the metal oxide film is doped with Te as a dopant. As a result, the film formation method according to the embodiment can form a metal oxide film with a high dielectric constant.

[0100] Furthermore, in step b), Te is doped at 3 at % or more, which allows the film deposition method according to the embodiment to deposit a metal oxide film with a higher dielectric constant.

[0101] In step b), Te is doped at 15 at % or less, whereby the film forming method according to the embodiment can form a metal oxide film that can suppress the occurrence of leakage current.

[0102] In addition, in step a), a metal oxide film having a tetragonal crystal structure is deposited, which allows the film deposition method according to the embodiment to deposit a metal oxide film with a higher dielectric constant.

[0103] In step a), a metal oxide film having a thickness of 10 nm or less is formed, whereby the film forming method according to the embodiment can effectively form a metal oxide film having a tetragonal crystal structure.

[0104] In step a), a metal oxide film having a monoclinic crystal structure is formed, and the film forming method according to the embodiment can increase the dielectric constant of the metal oxide film having a monoclinic crystal structure that is stable at room temperature.

[0105] In step b), the dopant is doped into the metal oxide film by any one of ion implantation, gas cluster ion beam, nanolaminate, dopant solution immersion, thermal diffusion doping, laser doping, flash lamp doping, and deposited film deposition. This allows the film forming method according to the embodiment to dope the dopant into the metal oxide film.

[0106] The metal oxide film is a ZrO2 film, a HfO2 film, or a mixed film of ZrO2 and HfO2. The film forming method according to the embodiment further includes step c), which is a step performed before step a). Step c) includes forming a thin film 20 of one or both of ZrO2 and HfO2, treating the surface of the thin film 20 with any one of sulfuric acid, phosphoric acid, hydrogen peroxide, dilute hydrofluoric acid, hydrochloric acid, and ammonia, or a mixture of two or more of these chemicals, and then baking the thin film. In step c), after baking, the surface is further cleaned and dried to remove any remaining chemical or mixture from the surface. As a result, the film forming method according to the embodiment can stably form a ZrO2 film, HfO2 film, or mixed film of ZrO2 and HfO2 with a tetragonal crystal structure on the thin film 20 in step a).

[0107] It should be noted that the disclosed embodiments are illustrative in all respects and should not be considered limiting. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

[0108] Furthermore, the following supplementary notes are disclosed regarding the above-described embodiment.

[0109] (Appendix 1) a) forming a ZrO2 film, a HfO2 film, or a mixed film of ZrO2 and HfO2 as a metal oxide film; b) doping the metal oxide film with Te as a dopant; A film forming method comprising:

[0110] (Appendix 2) 2. The film forming method according to claim 1, wherein in the step b), Te is doped at 3 at % or more.

[0111] (Appendix 3) 3. The film forming method according to claim 2, wherein in the step b), Te is doped at 15 at % or less.

[0112] (Appendix 4) 4. The film forming method according to any one of claims 1 to 3, wherein in the step a), the metal oxide film having a tetragonal crystal structure is formed.

[0113] (Appendix 5) 5. The film forming method according to claim 4, wherein in the step a), the metal oxide film is formed to a thickness of 10 nm or less.

[0114] (Appendix 6) 4. The film forming method according to any one of claims 1 to 3, wherein in the step a), the metal oxide film having a monoclinic crystal structure is formed.

[0115] (Appendix 7) 7. The film forming method according to any one of appendixes 1 to 6, wherein in the step b), the dopant is doped into the metal oxide film by any one of an ion implantation method, a gas cluster ion beam method, a nanolamination method, a spin coating method, a dopant solution immersion method, a thermal diffusion doping method, a laser doping method, a flash lamp method, and a deposited film method.

[0116] (Appendix 8) 8. The film forming method according to any one of claims 1 to 7, wherein in the step b), doping with Te is performed using a precursor made of an inorganic tellurium compound or an organic tellurium compound.

[0117] (Appendix 9) c) a step carried out before the step a), further comprising the steps of forming a thin film of one or both of ZrO2 and HfO2, treating the surface of the thin film with sulfuric acid or phosphoric acid, and then firing the thin film; 8. A film forming method according to any one of claims 1 to 7.

[0118] (Appendix 10) In the step c), after the firing, the surface is washed and dried to further remove sulfuric acid or phosphoric acid remaining on the surface. 9. The film forming method according to claim 8.

[0119] (Appendix 11) a film forming unit configured to form a ZrO2 film, a HfO2 film, or a mixed film of ZrO2 and HfO2 as the metal oxide film; a doping portion configured to dope the metal oxide film with Te as a dopant; A film forming apparatus comprising:

[0120] (Appendix 12) A semiconductor device having a metal oxide film, The metal oxide film is ZrO2 film, HfO2 film, or a mixed film of ZrO2 and HfO2, containing Te as a dopant; Semiconductor device. [Explanation of symbols]

[0121] 10 Film deposition equipment 11 Film forming section 12 Dope Section 20 Thin Films 21 Membrane 30 stages 31 Ion Source 32 Ion beam 34 small hole 40 stages 41 Piping 42 nozzles 43 Ionizer 44 Acceleration section 45 Magnet 46 Neutralization Department 47 Aperture 51 Metal oxide film 52 membrane 61 Metal oxide film 62 Dopant Solution 71 Chamber 72 Heat source 81 Chamber 82 Stages 83 Transparent window 84 Laser light 91 Chamber 92 Stages 93 Heater 94 Transparent part 95 Flash Lamp 96 Reflector 99 Sacrificial Film W substrate

Claims

1. a) As a metal oxide film, ZrO ２ membrane, HfO ２ film, or ZrO ２ and HfO ２ forming a mixed film of the above; b) doping the metal oxide film with Te as a dopant; A film forming method comprising:

2. 2. The film forming method according to claim 1, wherein in the step b), the film is doped with Te at 3 at % or more.

3. 3. The film forming method according to claim 2, wherein in the step b), Te is doped at 15 at % or less.

4. 2. The film forming method according to claim 1, wherein in the step a), the metal oxide film is formed to have a tetragonal crystal structure.

5. 5. The film forming method according to claim 4, wherein in the step a), the metal oxide film is formed to a thickness of 10 nm or less.

6. The film forming method according to claim 1 , wherein in the step a), the metal oxide film is formed to have a monoclinic crystal structure.

7. 2. The film forming method according to claim 1, wherein in the step b), the dopant is doped into the metal oxide film by any one of an ion implantation method, a gas cluster ion beam method, a nanolaminate method, a spin coating method, a dopant solution immersion method, a thermal diffusion doping method, a laser doping method, a flash lamp method, and a deposited film method.

8. 2. The film forming method according to claim 1, wherein in the step b), Te is doped using a precursor made of an inorganic tellurium compound or an organic tellurium compound.

9. c) a step carried out before step a), comprising: ２ , HfO ２ and further comprising a step of forming a thin film by one or both of the above, treating the surface of the thin film with sulfuric acid or phosphoric acid, and then baking the thin film. The film forming method according to claim 1 .

10. In the step c), after the firing, the surface is washed and dried to further remove sulfuric acid or phosphoric acid remaining on the surface. The film forming method according to claim 8 .

11. As the metal oxide film, ZrO ２ membrane, HfO ２ film, or ZrO ２ and HfO ２ a film forming unit configured to form a mixed film of the above; a doping section configured to dope the metal oxide film with Te as a dopant; A film forming apparatus comprising:

12. A semiconductor device having a metal oxide film, The metal oxide film is ZrO ２ membrane, HfO ２ film, or ZrO ２ and HfO ２ It is a mixed film of containing Te as a dopant; Semiconductor device.

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